The case number is (circled in Green).
The six-digit serial number is (Circled in Red).
There are no "Calibre Numbers" beginning with an "S"; it will be a number 5.
The "Seiko Sales Code" begins with an "S" but is NOT on the watch. See the bottom of this page.
1M
1N
3M
4F
4M
4R
4T
5D
5J
5M
5M GMT
5R
5Y
5
6A
6L
6M
6R
6T
7A
7D
7L
7M
7N
7S
7T
8F
8M
8L
8R
8T
9R
9S
9T
NE
NH
V
V Chronograph
Y
YT
Seiko Sales Code Letters (They are not on the watch)
SAA
SAR
SBS
SCD
SCX
SDM
SEH
SEJ
SFG
SFJ
SFK
SGT
SHF
SHG
SHS
SJQ
SKA
SKH
SKJ
SKX
SKZ
SLA
SLL
SLQ
SLR
SLT
SMA
SMW
SMY
SNE
SNG
SNK
SNL
SNP
SNQ
SNX
SPB
SPR
SRG
SRH
SRN
SRP
SRX
SSC
SSB
SUN
SUZ
SWE
SWD
SWP
Odds
5 BAR
10 BAR
20 BAR
50 M.
100 M.
200 M.
Automatic.
Arctura.
Oakley Timebomb.
5
SLQ
Solar
Solar Chronograph
SQ50.
SQ100.
SQ200.